1.4C Impacts of Tectonic Hazards

The social and economic impacts of tectonic hazards (volcanic eruptions, earthquakes and tsunami) on the people, economy, and environment of contrasting locations in the developed, emerging and developing world. 

The impacts of tectonic hazards are broadly of three types:
  1. social - deaths, injury and wider health impacts including psychological ones
  2. economic - the loss of property, businesses, infrastructure and opportunity
  3. environmental - damage or destruction of physical systems, especially ecosystems

In the last 30 years, different tectonic hazards have had contrasting impacts in terms of scale. 
Volcanic eruptions: Small and declining impacts, especially death tolls
Earthquakes: Large impacts, as significant earthquakes are common and widespread
Tsunami: Very large impacts from a small number of events

Comparing impacts between countries is difficult because both the physical nature of the event and the socio-economic profiles of affected places are different. Some general observations are:
  • economic costs in developed and emerging economies are, in some cases, enormous
  • deaths in developed countries are low, except for the 2011 Japanese tsunami (a very rare megadisaster)
  • volcanic eruption impacts are small compared with those of earthquakes and tsunami

Volcanic eruptions 
​
2002 Nyiragongo (DRC)

About:
  • Constructive margin, continental rift zone
  • Basaltic magma
  • Composite cone volcano (a..k.a. stratovolcano)
  • VEI = 1
Social Impacts
  • 147 deaths
  • 120,000 made homeless
Economic Impacts
  • 15% of the city of Goa destroyed by lava flows
  • US $1.2 billion in economic losses
Environmental Impacts
Response
  • Major international aid response launched


2010 Merapi (Indonesia)

About
  • Destructive margine subduction zone
  • Andesitic magma
  • Composite cone volcano
  • VEI = 4

Social Impacts:​
  • 353 deaths
  • about 500 injured
  • 350,000 people evacuated before the eruption
​Economic Impacts:
  • $0.6 billion in losses
  • Loss of rice harvest due to ash fall
Environmental Impacts:
  • Some destruction of forests due to pyroclastic flows


2010 Eyjafjallajökull (Iceland)

About:
  • Constructive margin
  • Mid-ocean ridge
  • Basaltic magma
  • Composite cone volcano (stratovolcano)
  • VEI = 4 (same year and VEI as Merapi)

Social Impacts:​
  • No injuries
  • No deaths
​Economic Impacts:
  • Major disruption to European and transatlantic air travel affecting 10 million passengers
    • and costing $10 million in economic losses
Environmental Impacts:
  • Ice melt on the volcano caused some flash flooding



Earthquakes

2015 Gorkha (Nepal)

  • Magnitude = 7.9
  • Focal depth = 8.2 km
  • Continent-continent collision zone

Social Impacts:​
  • 9000 deaths
  • 22,000 injured
  • Many rural villages totally destroyed
​Economic Impacts:
  • $5 billion in losses
  • Many rural villages totally destroyed
Environmental Impacts:
  • Some destruction of forests due to pyroclastic flows
  • Killer avalanches triggered on Mount Everest


​2008 Sichuan (China)

About
  • Magnitude 8.0
  • Focal depth = 19 km
  • Continent-continent collision zone (same as Gorkha)

Social Impacts:​
  • 69,000 deaths
    • About 1/3 of deaths (23,000) due to landslides 
  • 370,000 injured
  • At least 5 million homeless
​Economic Impacts:
  • More than $140 billion in losses
Environmental Impacts:​


2010 Canterbury (New Zealand)

About:
  • Magnitude 7.1
  • Focal depth = 10 km
  • Subduction zone

Social Impacts:​
  • 100 injuries
  • No deaths (same as Eyjafjallajokull)
  • A magnitude 6.3 aftershock in Christchurch killed 185 people
Economic Impacts:
  • $40 in total losses (including aftershocks)
  • Widespread building damage due to liquefaction
Environmental Impacts:
​


Tsunami

2004 Indian Ocean

About:
  • Magnitude 9.2
  • 24 m tsunami height
  • Megathrust subduction zone
Social Impacts:​
  • 230,000 deaths
  • 125,000 injured
  • 1.7 million people displaced across 15 countries
​Economic Impacts:
  • ​$15 billion in economic losses
Environmental Impacts:


2010 Talcahuano (Chile)

About:
  • Magnitude 8.8
  • 2.6 m tsunami height
  • Megathrust subduction zone
  • Overall, the earthquake was more damaging than the accompanying tsunami

Social Impacts
  • 525 deaths
  • Felt by 80% of the population
  • Blackout that affected 93% of the population
Economic Impacts
  • 370,000 homes damaged
  • Economic costs of $15-30 billion to Chile, and $67 million to Japan (fishing in Tôhoku)
Environmental Impacts
​

2011 Tôhoku (Japan)

About: 
  • Magnitude 9.0 (median of Talcahuano and Indian Ocean)
  • 9.3 m tsunami height
  • Megathrust subduction zone (all are)

Social impacts
  • 16,000 deaths
  • 6000 injuries
Environmental impacts
  • $300 billion in economic losses 
  • 46,000 buildings destroyed
  • 145,000 buildings damaged
  • Huge infrastructure damage to ports, water and electricity supply